Your Japanese Fleet, consisting of 4 Carrier, 1 Battleship, 8 Fighter will have to fight most likely:
1 Bomber, 1 Tac, 5 Fighter, 2 Battleships, 2 Carrier, 2 Destroyer, 2 Crusier, 1 Sub (another figther, Destroyer and sub is likely and at least one mor ship).
You need to bring another 4 ships (2 crusier, 2 destroyer) or it will be close.
first combat round:
Japan scores 9@4 ~ 6, 4@2 ~ 1 (7 hits)
US scores: 3@4 ~ 2, 7@3 ~ 3, 3@2 ~ 1 (6 hits)
second round: (all capital ships hit once and one carrier sunk):
JAPAN: 9@4 ~ 6, 3@2 ~ 1 (7 hits)
USA (2 Carrier Sunk, 1 battleship hit, 2 destroyer sunk):
US: 3@4 ~ 2, 7@3 ~ 4, 1@2 ~0 (6 hits) (7@3 ~3,5 hits, in two turns of combat 7 hits, oce 3 once 4)
Leaves: Japan looses: 3 Carrier and 3 Fighter, US looses: 2 Crusier, 1 Sub and 4 fighter
Japan: 6@4 ~ 4 hits
US: 3@4 ~ 2hits, 1@3 ~0.5
Leaves the Japanese navy with 1 damaged battleship, and 2 Fighter.
This navy cant threaten an attack on Australia and will give the UK Player the oportunity to start an large scale attack on Japan and its remaining small fleet, while the US can and will build up another large Navy relatively fast (much more income than Japan).
I thikn, this is the way to loose the pacific fast to the allies, and therefore to loose the game, because the US only needs to invet 2 more turns to secure the pacific and then can focus on Europe.
my 2 cents